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Natural variation in fruit characteristics and seed germination of
Jatropha curcas in Benin, West Africa
By E.A. PADONOU1*, B. KASSA1, A. E. ASSOGBADJO1, B. FANDOHAN1, S. CHAKEREDZA2,
R. GLÈLÈ KAKAÏ1and B. SINSIN1
1Faculty of Agronomic Sciences, University of Abomey-Calavi, 01 P. O. Box 526, Cotonou, Benin
2African Network for Agriculture, Agroforestry and Natural Resources Education, United Nations
Avenue P. O. Box 30677-00100, Nairobi, Kenya
(e-mail: padonouelie@gmail.com) (Accepted 19 July 2013)
SUMMARY
An investigation was conducted in the ten phytodistricts of Benin, West Africa, in order to assess the level of
morphological variation in Jatropha curcas seed and their germination potential. Hierarchical classification of the
morphological traits of seeds identified five morphotypes, using 54% of the overall morphological information.
Canonical discriminant analysis performed on the five morphotypes revealed highly significant differences.
Morphotype 1 included seeds from the phytodistricts of Côtier, Pobè, The Ouémé Valley, and Plateau. Morphotype 2
and Morphotype 5 seeds were from the phytodistricts of Bassila, Zou, and Borgou-Sud; while Morphotype 3 and
Morphotype 4 seeds were from the phytodistricts of Borgou-Nord, the Atacora Chain, and Mekrou-Pendjari.
Significant morphological variation existed within the seeds as a consequence of genetic make-up and/or
environmental effects. Seed from Mekrou-Pendjari and the Atacora Chain were black, smooth, light (0.67 g seed–1),
and small (1.76 cm-long and 1.15 cm-wide). Seed from Plateau,Côtier,The Ouémé Valley, and Pobè zones were brown,
rough, heavy (0.84 g seed–1), and large (1.97cm-long, 1.2 cm-wide). All seed germination started 4 d after sowing and
ended between day-7 and day-8. Seed germination timing varied significantly with morphotype.
Attempts are now being made to promote the
widespread cultivation of plants or crops previously
grown only in localised areas. Species such as Jatropha
curcas L., which can be grown for processing into
biodiesel, have captured the attention of researchers in
temperate and tropical zones.J. curcas is well-adapted to
semi-arid marginal areas. The oil from J. curcas can be
processed and used as a substitute for diesel fuel, while
growing the plant can control soil erosion (Heller, 1996;
Foidl and Elder, 1997; Subramanian et al., 2005). The
seeds, leaves, and bark of J. curcas are also used in
traditional medicine and for veterinary purposes
(Assogbadjo et al., 2009). J. curcas can be propagated by
cuttings and through seed. If propagated by seed, the
plant develops a single tap-root structure (Padonou,
2009). However,low seed viability limits the efficiency of
propagation by seed (Gadekar, 2006). When using
cuttings,no tap-root will develop and the root system will
develop into a dense and superficial carpet of
adventitious roots, suitable for preventing soil erosion
and for accumulating sediment, but vulnerable to
landslides and uprooting by wind (Padonou, 2009).
Such a multiple-use crop requires genetic
improvements to promote cultivation for oil production,
the prevention of erosion, as well as medical and
veterinary purposes. Currently, crop improvement in J.
curcas has been limited (Ginwal et al., 2005). J. curcas has
high economic importance in Benin. Indeed, J. curcas
plants were exported from Benin to France in the 1940s
for the production of household soap and were widely
used as hedges in the North of Benin in the 1990s (Global
Facilitation Unit for Underutilized Species, 2007).
However, few scientific data are available on the natural
variation in seed morphology and seed germination in this
species in Benin (Assogbadjo et al., 2008; 2009; Padonou,
2009) although J. curcas has recently been considered by
the Benin Government as a priority tree species to be
developed in agroforestry systems for bio-fuel production.
In addition, significant genetic variation exists in seed
morphology and in the oil content of Jatropha seed.This is
important for tree improvement programmes.
Unfortunately, little work has been done on germplasm
conservation (Kumar and Sharmar, 2008). Kaushik et al.
(2007) reported some variation in seed traits and oil
contents in 24 accessions of J. curcas collected in Haryana
State, India. Consequently, one important question to be
addressed was the possible link between seed morphology
and environmental factors (or phytodistricts) in Benin.
Since no information was currently available, the first
objective of the present study was to assess the level of
natural variation in seed morphology in order to identify
morphotypes of J. curcas based on seed characteristics.If
the morphological variation in seeds could be correlated
with their provenance and/or linked to their germination
parameters, it would be possible to predict which seed
provenances were most suitable for large-scale
propagation. The second objective of this study was to
compare the rates of germination and the germination
parameters of the different morphotypes of J. curcas
seed, our hypothesis being that there was a strong
correlation between the morphological variation in seed
and their germination ability.
*Author for correspondence.
Journal of Horticultural Science & Biotechnology (2014) 89 (1) 69–73
Variation in Jatropha curcas seed in Benin
MATERIALS AND METHODS
Seeds of J. curcas were collected from each of the ten
phytogeographical districts (phytodistricts) of Benin,
(Figure 1). Ten trees, spaced at least 100 m from each
other to avoid narrowing the genetic base due to
relatedness or inbreeding, were selected and sampled in
plantations in each of the ten phytodistricts, as
recommended by Turnbull (1975). Mature black fruit
(n = 10) were collected directly from each tree.A total of
100 seeds were therefore collected at random in each
phytodistrict.
The colours of the dried seeds of J. curcas were
determined using a standard colour chart (Royal
Horticultural Society, 1966). Seeds were coded 1 if black,
or 0 if brown. The length, width, and thickness of each
seed were measured using electronic calipers. Seed
texture was determined by touch, and coded 1 if rough,
or 0 if smooth. The weight of each seed was measured
using an electronic balance with a sensitivity of 0.0001 g.
Seed length, width, thickness, weight, colour, and
texture data were subjected to an Ascending
Hierarchical Classification (AHC) using SAS statistical
software (SAS, 2003). This enabled classification of the
seeds based on similar morphological traits. Canonical
discriminant analysis was then performed on the
morphotypes identified from the AHC in order to
validate and test the differences between morphotypes.
The clusters (considered to be morphotypes) of J. curcas
seed were also defined by their differences, using
discriminant axes defined by the seed traits being
measured. The same analysis was also performed to test
and describe the differences between the ten
phytodistricts according to the morphological
parameters of the J. curcas seed.
Five morphotypes were identified from the AHC. Five
seeds of each morphotype were sown in a single pot
made from a polythene bag measuring 5.5 cm 18 cm
and filled with forest soil. Ten pots were used for each
morphotype. The experimental units (all pots) were
arranged in a randomised block design with three
replicates. For each morphotype, the number of seeds
that germinated in all ten pots was recorded each day
over a 10 d period. The nursery experiment was carried
out at the University of Abomey-Calavi,located between
6°21’ – 6°42’N and 2°13’ – 2°25’E in the Côtier
phytodistrict, in March 2009 (Figure 1).
The germination percentage of each morphotype of J.
curcas seed was calculated each day over 10 d and used
to measure the effect of time and morphotype on the
rate of germination of J. curcas seed. The statistical test
used was analysis of variance on repeated measures
(Crowder and Hand, 1990) available in SAS statistical
software (SAS, 2003), using the mixed model. In this
model, the factor “block” was considered to be random,
whereas the factor “morphotype” was considered to be
fixed. No data transformation was applied to the
germination percentages because normality and
homoscedasticity were checked without transformation
using the Ryan-Joiner test of normality and the Levene
70
TABLE I
Characteristics of the ten phytogeographical districts of Benin
PChor‡Phytogeographic district R¶Rainfall (mm) Major soil type Major plant formation
GCR Côtier Bi 900–1,300 Sandy + hydromorphic & Coastal forest and derived thickets,
allomorphic soils mangrove
GCR Pobè Bi 1,200–1,300 Ferralitic soils without concretions Semi-deciduous forest
GCR Plateau Bi 900–1,100 Ferralitic soils without concretions Semi-deciduous forest
GCR Vallée de l’Ouémé Bi 1,100–1,300 Hydromorphic soils Swamp and semi-deciduous forest
SGR Bassila TUn 1,100–1,300 Ferralitic soils with concretions and Semi-deciduous forest, woodland, and
breastplates riparian forest
SGR Zou TUn 1,100–1,200 Ferruginous soils on crystalline rocks Dry forest, woodland, and riparian forest
SGR Borgou-Sud TUn 1,100–1,200 Ferruginous soils on crystalline rocks Dry forest, woodland, and riparian forest
SR Borgou-Nord Un 1,000–1,200 Ferruginous soils on crystalline rocks Dry forest, woodland, and riparian forest
SR Chaîne de l’Atacora Un 1,000–1,200 Poorly evolved & mineral soils Riparian forest, dry forest, and woodland
SR Mékrou-Pendjari Un 950–1,000 Ferruginous soils with concretions Tree and shrub savannahs, dry forest and
on sedimentary rocks riparian forest
‡PChor, phytochorological zones based on the composition in distribution range types; GCR, Guineo-Congolian region; SGR, Sudano-Guinean
transition zone; SR, Sudanian region.
¶R, rainfall regime; Bi, bimodal (two rainy seasons);TUn, tendency to unimodal; Un, unimodal (one rainy season).
FIG.1
The ten phytogeographical districts (phytodistricts) of Benin, West
Africa. Inset shows the location of Benin.The black triangle marks the
location of the township of Abomey-Calavi.
0º0'0"E 1º0'0"E 2º0'0"E 3º0'0"E 4º0'0"E
7º0'0"N 8º0'0"N 9º0'0"N 10º0'0"N 11º0'0"N 12º0'0"N
E. A. PADONOU,B.KASSA,A.E.ASSOGBADJO,B.FANDOHAN,S.CHAKEREDZA,R.GLÈLÈ KAKAÏ
and B. SINSIN
test for homogeneity of variances (Glèlè Kakaï et al.,
2006).
RESULTS
Identification of J. curcas morphotypes
Five clusters (morphotypes) were identifed from the
AHC using 54.2% of the information recorded on all
seeds. The results of canonical discriminant analysis
performed on the five morphotypes of J. curcas seed
showed that the Mahalanobis distances between pairs of
the five clusters identified were all highly significant (P≤
0.001). The morphotypes identified from the AHC were
therefore different according to the morphological traits
of J. curcas seed. Morphotype 1 was derived from the
Côtier, Pobè, The Ouémé Valley, and Plateau
phytodistricts. Morphotypes 2 and 5 were from the
Bassila, Zou, and Borgou-Sud phytodistricts; whereas
Morphotypes 3 and 4 were from Borgou-Nord, the
Atacora Chain, and Mekrou-Pendjari phytodistricts.
Other results from the canonical discriminant analysis
performed on individuals of the five seed morphotypes
revealed that the first two axes were significant (P≤
0.05) and explained 61.6% of the variation seen in the
morphotypes.The coefficient of correlation between the
two canonical axes (Can) and the morphological traits of
J. curcas seed indicated that the first axis (Can 1)
discriminated the morphotypes according to seed colour,
texture, and weight. On this axis, heavy seeds were also
often black and smooth. The second axis (Can 2)
discriminated the five morphotypes according to the size
of the seed. It showed that long seeds were also wide and
thick.
Seeds from Morphotype 3 and Morphotype 4 were
black, light, and smooth, while seeds from Morphotype 1
were brown, heavy, and rough (Figure 2). Most seeds
from Morphotype 2 and Morphotype 5 were brown,
heavy, and rough, but some were dark, light, and smooth.
The Can 2 axis (Figure 2) discriminated the five
morphotypes according to the size of their seed. For
example,Morphotype 2 and Morphotype 3 differed from
Morphotype 4 and Morphotype 5 according to the
length, width, and thickness of their seed. Seeds from
Morphotype 2 and Morphotype 3 were the smallest. A
more detailed description of each morphotype is
provided in Table II, from which we observed that
Morphotype 5 had the longest seeds (mean = 1.91 cm),
while the shortest seeds were from Morphotype 3 (mean
= 1.77 cm). The widest seeds were found in Morphotype
1 and Morphotype 4 (mean = 1.2 cm), whereas the
thinnest seeds were from Morphotype 3 (mean = 1.08
cm). With regard to seed weight, those of Morphotype 1
were the heaviest (mean = 0.80 g), while the lightest seed
were grouped in Morphotype 2 (mean = 0.66 g).
On the basis of the ten phytodistricts, we noticed that
seeds collected from Mekrou-Pendjari or the Atacora
Chain were black, smooth, lightweight (mean = 0.67 g),
short (mean = 1.76 cm), and thin (mean = 1.15 cm),while
seeds from Plateau, Côtier,The Ouémé Valley, and Pobè
were brown, rough,heavy (mean = 0.84 g), long and wide
(mean length = 1.92 cm; mean width = 1.2 cm). Seeds
from Zou, Borgou-Sud, and Bassila were black, smooth,
and heavy, but some had the opposite features (Table
III).
Germination ability of J. curcas seed according to
morphotype
The germination ability of each seed morphotype
varied over time between sowing and 10 d after sowing
(Table IV). The germination percentages of seeds also
varied throughout the 10 d.The blocking factor and all its
interactions were non-significant, indicating
homogeneity of the environmental characteristics within
and between the blocks.Morphotypes 1, 2, and 3 showed
a rapid increase in germination percentage from 4 d to 10
d after sowing (Figure 3). Morphotypes 4 and 5 showed
less variation in germination percentage over time.
71
FIG.2
Projection of the five morphotypes of J. curcas seed on the canonical
axes defined by morphological traits. Can 1 discriminated on seed
colour, texture and weight. Can 2 discriminated on seed size.
TABLE II
Mean values and standard deviations of traits in the five morphotypes of J. curcas seed
Seed trait Morphotype 1 Morphotype 2 Morphotype 3 Morphotype 4 Morphotype 5
Length (cm) 1. 87 ± 0.09†1.80 ± 0.12 1.77 ± 0.10 1.85 ± 0.10 1.91 ± 0.09
Width (cm) 1. 20 ± 0.01 1.11 ± 0.06 1.09 ± 0.03 1.20 ± 0.01 1.18 ± 0.07
Thickness (cm) 0.73 ± 0.05 0.71 ± 0.07 0.69 ± 0.05 0.73 ± 0.07 0.98 ± 0.07
Weight (g) 0.80 ± 0.07 0.66 ± 0.16 0.72 ± 0.09 0.71 ± 0.09 0.74 ± 0.11
Colour Brown Black/Brown Black Black Black/Brown
Texture Rough Smooth/Rough Smooth Smooth Smooth/Rough
†All values are means (n = 1,000) ± SD.
1. Seed morphotype 1
2. Seed morphotype 2
3. Seed morphotype 3
4. Seed morphotype 4
5. Seed morphotype 5
6. Seed morphotype 6
Can 2
Can 1
Variation in Jatropha curcas seed in Benin
DISCUSSION
Morphological variation in J. curcas seed
This study on the morphological characteristics of J.
curcas seed identified five morphotypes in Benin. These
morphotypes were significantly different according to
their morphological traits, as revealed by canonical
discriminant analysis. This morphological variation in J.
curcas seed was similar to that observed by Ginwal et al.
(2005) in India. Some studies dealing with different plant
species have reported that morphological characteristics
vary with climatic region and ecological gradient.
Maranz and Wiesman (2003) showed a significant
relationship between trait values (e.g., fruit size and
shape, pulp sweetness, and kernel content of the species)
and abiotic variables (e.g., temperature and rainfall) in
sub-Saharan Africa (North of the Equator) for shea
butter trees (Vitellaria paradoxa). Soloviev et al. (2004)
also reported a significant influence of the climatic zones
of Senegal on fruit pulp production in Balanites
aegyptiaca and Tamarindus indica. Therefore, the
phenotypic differences between morphotypes of J.
curcas seed could also be explained by environmental
factors. In fact, apart from the ages and genotypes of the
trees, the soil and climate where they grew were
important factors that affected the morphological traits
of the seed and fruit (Salazar and Quesada, 1987;
Assogbadjo et al., 2005; 2006).
In this study, we noticed that part of the morphological
variation in J. curcas seed could be explained by the
phytodistrict in which the seeds were collected.
Nevertheless, an important overlap between the
provenance of J. curcas seed in Benin has been observed,
indicating that factors other than environment affect seed
morphology. The morphological differences between
seeds could also be of genetic origin, resulting from
adaptation of the species to diverse environmental
conditions (Mathur et al., 1984).This genetic variation, if it
exists, could be an important source for varietal selection.
Seed germination
Rai and Tripathi (1982) reported the positive influence
of a large seed size and seed reserves on the
establishment and early growth of seedlings. In that
respect, one can expect some variation in the rates of
seed germination among the five morphotypes identified
in J. curcas. Indeed, phenotypic variation is generally
assumed to reflect the inherent genotypic variation
among and within groups of plants growing under the
same environmental conditions. In our study, the
germinating ability of J. curcas seed showed significant
variation between morphotypes. The lowest rate of
germination at the end of the experiment was 50%,
recorded for Morphotype 4, while the highest rate of
germination (89%) was recorded for Morphotype 2.This
could reflect genetic variation between these
morphotypes. The differences observed in seed
germination rate could be considered genetic, because
environmental variation at the experimental site was
negligible, and the experimental design reduced any
residual variation that could persist on site. It has been
reported that genotype has a strong influence on seed
vigour (Schmidt, 2000). Since the five morphotypes
consisted of seeds from different sites, the J. curcas
populations we sampled would have restricted gene flow,
which may lead to discontinuous variation in seed
germination characteristics, which are genetically
controlled (Whittington, 1973).
72
FIG.3
Trends in the rates of germination of J. curcas seed according to
morphotype.
TABLE III
Morphometric traits of J. curcas seed from the ten phytodistricts of Benin
PChor‡Phytodistrict Length (cm) Width (cm) Thickness (cm) Weight (g) Seed colour Seed texture
RGC Côtier 1.85 ± 0.10†1.2 ± 0.00 0.76 ± 0.08 0.77 ± 0.10 Brown Rough
RGC Pobè 1.86 ± 0.07 1.18 ± 0.03 0.71 ± 0.06 0.83 ± 0.09 Brown Rough
RGC Plateau 1.85 ± 0.11 1.16 ± 0.06 0.77 ± 0.10 0.76 ± 0.11 Brown Rough
RGC Ouémé Valley 1.97 ± 0.05 1.2 ± 0.00 0.76 ± 0.05 0.84 ± 0.12 Brown Rough
SGR Bassila 1.85 ± 0.08 1.16 ± 0.05 0.77 ± 0.12 0.72 ± 0.12 Black/Brown Smooth/Rough
SGR Zou 1.87 ± 0.10 1.16 ± 0.07 0.78 ± 0.13 0.75 ± 0.09 Black/Brown Smooth/Rough
SGR Borgou-Sud 1.81 ± 0.13 1.16 ± 0.05 0.76 ± 0.10 0.74 ± 0.10 Black/Brown Smooth/Rough
RS Borgou-Nord 1.83 ± 0.08 1.15 ± 0.05 0.73 ± 0.00 0.70 ± 0.08 Black Smooth
RS Atacora Chain 1.77 ± 0.10 1.15 ± 0.06 0.74 ± 0.10 0.69 ± 0.10 Black Smooth
RS Mékrou-Pendjari 1.80 ± 0.12 1.16 ± 0.06 0.72 ± 0.08 0.66 ± 0.11 Black Smooth
‡PChor, phytochorological zones based on the composition and the types of distribution of species; RGC, Guineo-Congolian zone; SGR, Sudano-
Guinean transition zone; RS, Sudanian zone.
†All values are means (n = 1,000) ± SD.
TABLE IV
Analysis of variance on repeated measures related to the germination
ability of the five morphotypes of J. curcas seed
Source DF‡Type III SS¶Mean Square F-Value
Time (T) 9 55.58 6.18 1,615.66***
Block (B) 2 0.00 0.01 0.16ns
T x B 18 0.01 0.01 0.17ns
Morphotype (M) 4 3.11 0.78 83.40***
T x M 36 2.34 0.06 17.00***
B x M 8 0.01 0.01 0.07ns
T x B x M 72 0.03 0.01 0.12ns
‡DF, degrees of freedom.
¶Type III SS,Type III Sum of Squares; F-value, Fisher value.
ns, non-significant at P≥0.05; ***, significant at P≤0.001.
Time after sowing (d)
Germination percentage (%)
Morphotype 1
Morphotype 2
Morphotype 3
Morphotype 4
Morphotype 5
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